| 1 | =pod
|
|---|
| 2 |
|
|---|
| 3 | =head1 NAME
|
|---|
| 4 |
|
|---|
| 5 | EVP_KDF-X963 - The X9.63-2001 EVP_KDF implementation
|
|---|
| 6 |
|
|---|
| 7 | =head1 DESCRIPTION
|
|---|
| 8 |
|
|---|
| 9 | The EVP_KDF-X963 algorithm implements the key derivation function (X963KDF).
|
|---|
| 10 | X963KDF is used by Cryptographic Message Syntax (CMS) for EC KeyAgreement, to
|
|---|
| 11 | derive a key using input such as a shared secret key and shared info.
|
|---|
| 12 |
|
|---|
| 13 | =head2 Identity
|
|---|
| 14 |
|
|---|
| 15 | "X963KDF" is the name for this implementation; it
|
|---|
| 16 | can be used with the EVP_KDF_fetch() function.
|
|---|
| 17 |
|
|---|
| 18 | =head2 Supported parameters
|
|---|
| 19 |
|
|---|
| 20 | The supported parameters are:
|
|---|
| 21 |
|
|---|
| 22 | =over 4
|
|---|
| 23 |
|
|---|
| 24 | =item "properties" (B<OSSL_KDF_PARAM_PROPERTIES>) <UTF8 string>
|
|---|
| 25 |
|
|---|
| 26 | =item "digest" (B<OSSL_KDF_PARAM_DIGEST>) <UTF8 string>
|
|---|
| 27 |
|
|---|
| 28 | These parameters work as described in L<EVP_KDF(3)/PARAMETERS>.
|
|---|
| 29 |
|
|---|
| 30 | =item "key" (B<OSSL_KDF_PARAM_KEY>) <octet string>
|
|---|
| 31 |
|
|---|
| 32 | The shared secret used for key derivation.
|
|---|
| 33 | This parameter sets the secret.
|
|---|
| 34 |
|
|---|
| 35 | =item "info" (B<OSSL_KDF_PARAM_INFO>) <octet string>
|
|---|
| 36 |
|
|---|
| 37 | This parameter specifies an optional value for shared info.
|
|---|
| 38 |
|
|---|
| 39 | =back
|
|---|
| 40 |
|
|---|
| 41 | =head1 NOTES
|
|---|
| 42 |
|
|---|
| 43 | X963KDF is very similar to the SSKDF that uses a digest as the auxiliary function,
|
|---|
| 44 | X963KDF appends the counter to the secret, whereas SSKDF prepends the counter.
|
|---|
| 45 |
|
|---|
| 46 | A context for X963KDF can be obtained by calling:
|
|---|
| 47 |
|
|---|
| 48 | EVP_KDF *kdf = EVP_KDF_fetch(NULL, "X963KDF", NULL);
|
|---|
| 49 | EVP_KDF_CTX *kctx = EVP_KDF_CTX_new(kdf);
|
|---|
| 50 |
|
|---|
| 51 | The output length of an X963KDF is specified via the I<keylen>
|
|---|
| 52 | parameter to the L<EVP_KDF_derive(3)> function.
|
|---|
| 53 |
|
|---|
| 54 | =head1 EXAMPLES
|
|---|
| 55 |
|
|---|
| 56 | This example derives 10 bytes, with the secret key "secret" and sharedinfo
|
|---|
| 57 | value "label":
|
|---|
| 58 |
|
|---|
| 59 | EVP_KDF *kdf;
|
|---|
| 60 | EVP_KDF_CTX *kctx;
|
|---|
| 61 | unsigned char out[10];
|
|---|
| 62 | OSSL_PARAM params[4], *p = params;
|
|---|
| 63 |
|
|---|
| 64 | kdf = EVP_KDF_fetch(NULL, "X963KDF", NULL);
|
|---|
| 65 | kctx = EVP_KDF_CTX_new(kdf);
|
|---|
| 66 | EVP_KDF_free(kdf);
|
|---|
| 67 |
|
|---|
| 68 | *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_DIGEST,
|
|---|
| 69 | SN_sha256, strlen(SN_sha256));
|
|---|
| 70 | *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SECRET,
|
|---|
| 71 | "secret", (size_t)6);
|
|---|
| 72 | *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_INFO,
|
|---|
| 73 | "label", (size_t)5);
|
|---|
| 74 | *p = OSSL_PARAM_construct_end();
|
|---|
| 75 | if (EVP_KDF_derive(kctx, out, sizeof(out), params) <= 0) {
|
|---|
| 76 | error("EVP_KDF_derive");
|
|---|
| 77 | }
|
|---|
| 78 |
|
|---|
| 79 | EVP_KDF_CTX_free(kctx);
|
|---|
| 80 |
|
|---|
| 81 | =head1 CONFORMING TO
|
|---|
| 82 |
|
|---|
| 83 | "SEC 1: Elliptic Curve Cryptography"
|
|---|
| 84 |
|
|---|
| 85 | =head1 SEE ALSO
|
|---|
| 86 |
|
|---|
| 87 | L<EVP_KDF(3)>,
|
|---|
| 88 | L<EVP_KDF_CTX_new(3)>,
|
|---|
| 89 | L<EVP_KDF_CTX_free(3)>,
|
|---|
| 90 | L<EVP_KDF_CTX_set_params(3)>,
|
|---|
| 91 | L<EVP_KDF_CTX_get_kdf_size(3)>,
|
|---|
| 92 | L<EVP_KDF_derive(3)>,
|
|---|
| 93 | L<EVP_KDF(3)/PARAMETERS>
|
|---|
| 94 |
|
|---|
| 95 | =head1 HISTORY
|
|---|
| 96 |
|
|---|
| 97 | This functionality was added in OpenSSL 3.0.
|
|---|
| 98 |
|
|---|
| 99 | =head1 COPYRIGHT
|
|---|
| 100 |
|
|---|
| 101 | Copyright 2019-2022 The OpenSSL Project Authors. All Rights Reserved.
|
|---|
| 102 |
|
|---|
| 103 | Licensed under the Apache License 2.0 (the "License"). You may not use
|
|---|
| 104 | this file except in compliance with the License. You can obtain a copy
|
|---|
| 105 | in the file LICENSE in the source distribution or at
|
|---|
| 106 | L<https://www.openssl.org/source/license.html>.
|
|---|
| 107 |
|
|---|
| 108 | =cut
|
|---|
